Diagnostic method for urinary tract infection

ABSTRACT

It has been demonstrated that the urinary level of HBP increases in individuals that have a urinary tract infection. Accordingly, the urinary level of HBP in an individual can be used to determine whether or not an individual has a urinary tract infection.

FIELD OF THE INVENTION

The invention relates to the diagnosis and treatment of urinary tractinfection.

BACKGROUND OF THE INVENTION

Urinary tract infection (UTI) is a common diagnosis that can result inserious complications in both children and adults. Efficient diagnosisand treatment is important to reduce the risk of renal failure andoveruse of antibiotics. Rapid and safe diagnostic methods are requiredas an alternative to bacterial cultures. Early treatment improvesprognosis of urinary tract infection, and therefore early diagnosis isvital. A reliable biological or clinical marker to determine as early aspossible whether or not an individual has a urinary tract infection isneeded.

SUMMARY OF THE INVENTION

Heparin-binding protein (HBP, CAP37, Azurocidin) is a glycosylated,single chain, positively charged 37 kDa inactive serine proteasehomologue exhibiting 44% sequence identity with human neutrophilelastase. The three dimensional structure of HBP has been published(Iversen et at Nat Struct Biol. 1997 April; 4(4):265-8). It is containedin the azurophilic granulae and secretory vesicles of human neutrophils(Lindmark et al, J Leukoc Biol 1999; 66(4):634-43 and Tapper et al,Blood 2000; 96:2329-2337). It is a multifunctional protein that has beenshown to induce vascular leakage by altering the Ca²⁺ balance of theblood vessel cytoskeleton (Gautam et al, Nature Medicine 2001;7(10):1123-7). The M-protein of group A streptococci (GAS) in complexwith fibrinogen has been shown to induce HBP release by stimulation ofthe B2-integrin receptor of neutrophils (Herwald et al, Cell 2004;116(3):367-79). LPS can also induce HBP release by an unknown mechanism(Rasmussen et al, FEBS Lett 1996; 390(1):109 12). The sequence of HBP ispublically available (for example as NCBI accession no. NP_(—)001691REGION: 27.248) and is reproduced below as SEQ ID NO.1

SEQ ID NO: 1 IVGGRKARPRQFPFLASIQNQGRHFCGGALIHARFVMTAASCFQSQNPGVSTVVLGAYDLRRRERQSRQTFSISSMSENGYDPQQNLNDLMLLQLDREANLTSSVTILPLPLQNATVEAGTRCQVAGWGSQRSGGRLSRFPRFVNVTVTPEDQCRPNNVCTGVLTRRGGICNGDGGTPLVCEGLAHGVASFSLGPCGRGPDFFTRVALFRDWIDGVLNNPGP

Urinary HBP levels in patients suspected of having a urinary tractinfection have not previously been investigated. The inventors haveshown for the first time that levels of HBP are increased in individualswith urinary tract infection. According to the invention there is thusprovided a method of identifying whether or not an individual hasurinary tract infection, which method comprises measuring HBP in theindividual and thereby determining whether or not the individual hasurinary tract infection.

The invention further provides:

-   -   an agent for the detection of HBP for use in determining whether        or not an individual has a urinary tract infection;    -   a test kit for use in a method for determining whether or not an        individual has a urinary tract infection, which test kit        comprises an agent for the detection of HBP in an individual;    -   a method of treating an individual for urinary tract infection        comprising:    -   (i) determining whether or not an individual has a urinary tract        infection using a method of the invention; and    -   (ii) administering to an individual identified in (i) as at        risk, a therapeutically effective amount of at least one agent        suitable for the treatment of urinary tract infection.

DESCRIPTION OF THE FIGURES

FIG. 1 shows Urine levels of HBP, U-WBC and IL-6. Each dot representsthe concentration in an individual urine sample of HBP (A and B), WBC (Cand D) and IL-6 (E and F). The four patients groups are described in theMethods section. Bars represent median of values. The suggested cut-offvalue for HBP is marked at 32 ng/ml, for WBC at 2 WBC/μL and for IL-6 10pg/mL.

FIG. 2 shows Urinary levels of HBP and IL-6 correlated to concentrationsof bacteria in urine Each dot represents the concentration in anindividual urine sample of HBP (A) and IL-6 (B). Bars represent medianof values.

FIG. 3 shows correlation between HBP and WBC in urine, and between IL-6and U-WBC in urine. Spearman's rank correlation coefficient (rho)=0.79indicate that there is a correlation between levels of HBP and WBC inurine (A). Spearman's rank correlation coefficient for IL-6 is 0.338.Each dot represents the concentration in an individual urine sample ofHBP, WBC and IL-6.

FIG. 4 shows Receiver-operating characteristics curves (ROC) of HBP andWBC in urine differentiating between UTI and no UTI. Areas under the ROCcurves (AUC) were 0.942 (95% confidence interval, 0.889-0.996) for HBP,0.808 (95% confidence interval, 0.675-0.941) for IL-6, 0.858 (95%confidence interval, 0.742-0.974) for WBC.

DETAILED DESCRIPTION OF THE INVENTION Diagnosis

The present invention relates to a method of identifying whether or nota subject has a urinary tract infection. The invention therefore relatesto the diagnosis of urinary tract infection.

The present inventors have for the first time investigated the level ofurinary HBP in patients suspected of having urinary tract infection. Theinventors have demonstrated that urinary HBP levels are elevated inpatients with urinary tract infection relative to those who do not haveurinary tract infection.

The individual under test is typically suspected of having a urinarytract infection. The individual is typically a mammal. The mammal istypically a human or a domestic mammal such as a horse, a cow, a sheep,a dog or a cat. The individual is preferably a human.

The individual under test may have one or more symptoms associatedurinary tract infections including for example fever, typically greaterthan 37.5° C., abdominal or back pain, and/or a positive nitrite test.

The level of HBP is typically measured in vitro in a sample obtainedfrom an individual. The sample typically comprises a body fluid of anindividual. A fluid sample may be a sample of blood, plasma, serum,urine, cerebrospinal fluid or joint fluid. The sample is preferably aurine sample.

According to the present invention, an increased level or concentrationof HBP compared with the baseline level or concentration indicates thatthe individual has a urinary tract infection. The baseline level istypically the level of HBP in an individual who does not have a urinarytract infection, or who is suspected of having a urinary tractinfection, but is subsequently confirmed to not have a urinary tractinfection. Thus the method according to the present invention mayinclude comparison of the level of HBP in the sample to that of abaseline level.

In accordance with the present invention the concentration of HBP isgreater than 15 ng/ml, preferably greater than 25 ng/ml, more preferablygreater than 30 ng/ml, more preferably greater than 32 ng/ml, morepreferably greater than 35 ng/ml, and most preferably greater than 50ng/ml in the sample. Such levels can be used to indicate that anindividual has a urinary tract infection.

In an alternative aspect, the method may comprise assessing the relativelevel or concentration of HBP in the sample compared to a baseline levelor concentration. Typically, a method wherein the level or concentrationof HBP in the sample is increased by at least 3 fold or 4 fold relativeto the baseline level or concentration of HBP is indicative of urinarytract infection.

Other markers may also be included in the analysis such as the whiteblood cell count (WBC), particularly the urine WBC, and/or IL-6. HBP mayalso be used in combination with the nitrite test.

Detection of HBP

The invention is typically carried out by measuring the level of HBP invitro in a sample obtained from the individual. The sample typicallycomprises a body fluid of the individual. A fluid sample may be a sampleof blood, plasma, serum, urine, cerebrospinal fluid or joint fluid. Thesample is preferably a urine sample.

The sample may be processed prior to being assayed, for example bycentrifugation. The sample may also be typically stored prior to assay,preferably below −70° C.

Standard methods known in the art may be used to assay the level of HBP.These methods typically involve using an agent for the detection of HBP.The agent typically binds specifically to HBP. The agent may be anantibody specific for HBP, an aptamer that binds to HBP, a serineproteinase inhibitor such as aprotinin, for example as described inPetersen et al, Eur J Biochem 1993; 271-9, or a soluble fragment of anintegrin, for example as described in Cai and Wright, S. D. J Exp Med1996; 184:213-23. By specific, it will be understood that the agent orantibody binds to HBP with no significant cross-reactivity to any othermolecule, particularly any other protein. For example, an agent orantibody specific for HBP will show no significant cross-reactivity withhuman neutrophil elastase. Cross-reactivity may be assessed by anysuitable method.

An antibody used in the method of the invention may either be a wholeantibody or a fragment thereof which is capable of binding to HBP. Theantibody may be monoclonal. Such a whole antibody is typically anantibody which is produced by any suitable method known in the art. Forexample, polyclonal antibodies may be obtained by immunising a mammal,typically a rabbit or a mouse, with HBP under suitable conditions andisolating antibody molecules from, for example, the serum of saidmammal. Monoclonal antibodies may be obtained by hybridoma orrecombinant methods.

Hybridoma methods involve immunising a mammal, typically a rabbit, a rator a mouse, with HBP under suitable conditions, then harvesting thespleen cells of said mammal and fusing them with myeloma cells. Themixture of fused cells is then diluted and clones are grown from singleparent cells. The antibodies secreted by the different clones are thentested for their ability to bind to HBP, and the most productive andstable clone is then grown in culture medium to a high volume. Thesecreted antibody is collected and purified.

Recombinant methods involve the cloning into phage or yeast of differentimmunoglobulin gene segments to create libraries of antibodies withslightly different amino acid sequences. Those sequences which give riseto antibodies which bind to HBP may be selected and the sequences clonedinto, for example, a bacterial cell line, for production.

Typically the antibody is a mammalian antibody, such as a primate,human, rodent (e.g. mouse or rat), rabbit, ovine, porcine, equine orcamel antibody. The antibody may be a camelid antibody or sharkantibody. The antibody may be a nanobody. The antibody can be any classor isotype of antibody, for example IgM, but is preferably IgG.

The fragment of whole antibody that can be used in the method comprisesan antigen binding site, e.g. Fab or F(ab)2 fragments or ScFV. The wholeantibody or fragment may be associated with other moieties, such aslinkers which may be used to join together 2 or more fragments orantibodies. Such linkers may be chemical linkers or can be present inthe form of a fusion protein with the fragment or whole antibody. Thelinkers may thus be used to join together whole antibodies or fragmentswhich have the same or different binding specificities, e.g. that canbind the same or different polymorphisms. The antibody may be abispecific antibody which is able to bind to two different antigens,typically any two of the polymorphisms mentioned herein. The antibodymay be a ‘diabody’ formed by joining two variable domains back to back.In the case where the antibodies used in the method are present in anyof the above forms which have different antigen binding sites ofdifferent specificities then these different specificities are typicallyto polymorphisms at different positions or on different proteins. In oneembodiment the antibody is a chimeric antibody comprising sequence fromdifferent natural antibodies, for example a humanised antibody.

Methods to assess HBP level typically involve contacting a sample withan agent or antibody capable of binding specifically to HBP. Suchmethods may include dipstick assays and Enzyme-linked ImmunosorbantAssay (ELISA). Typically dipsticks comprise one or more antibodies orproteins that specifically bind HBP. If more than one antibody ispresent, the antibodies preferably have different non-overlappingdeterminants such that they may bind to HBP simultaneously.

ELISA is a heterogeneous, solid phase assay that requires the separationof reagents. ELISA is typically carried out using the sandwich techniqueor the competitive technique. The sandwich technique requires twoantibodies. The first specifically binds HBP and is bound to a solidsupport. The second antibody is bound to a marker, typically an enzymeconjugate. A substrate for the enzyme is used to quantify theHBP-antibody complex and hence the amount of HBP in a sample. Theantigen competitive inhibition assay also typically requires anHBP-specific antibody bound to a support. An HBP-enzyme conjugate isadded to the sample (containing HBP) to be assayed. Competitiveinhibition between the HBP-enzyme conjugate and unlabeled HBP allowsquantification of the amount of HBP in a sample. The solid supports forELISA reactions preferably contain wells.

The present invention may also employ antibodies to HBP in directsensing techniques including but not limited to those based upon surfaceplasmon resonance, surface acoustic wave, quartz crystal microbalance,microcalorimetry or electrochemical impedance spectroscopy.

The present invention may also employ methods of measuring HBP that donot comprise antibodies. High Performance Liquid Chromatography (HPLC)separation and fluorescence detection is preferably used as a method ofdetermining the HBP level. HPLC apparatus and methods as describedpreviously may be used (Tsikas D et al. J Chromatogr B Biomed Sci Appl1998; 705:174-6) Separation during HPLC is typically carried out on thebasis of size or charge. Prior to HPLC, endogenous amino acids and aninternal standard L-homoarginine are typically added to assay samplesand these are phase extracted on CBA cartridges (Varian, Harbor City,Calif.). Amino acids within the samples are preferably derivatized witho-phthalaldehyde (OPA). The accuracy and precision of the assay ispreferably determined within quality control samples for all aminoacids.

The invention further provides a diagnostic kit that comprises means formeasuring the HBP level in an individual and thereby determining whetheror not the individual has a urinary tract infection. The kit typicallycontains one or more antibodies that specifically bind HBP. For example,the kit may comprise a monoclonal antibody, a polyclonal antibody, asingle chain antibody, a chimeric antibody, a CDR-grafted antibody or ahumanized antibody. The antibody may be an intact immunoglobulinmolecule or a fragment thereof such as a Fab, F(ab′)₂ or Fv fragment. Ifmore than one antibody is present, the antibodies preferably havedifferent non-overlapping determinants such that they may bind to HBPsimultaneously.

The kit may additionally comprise means for the measurement of otherlaboratory or clinical parameters. For example the kit may comprisemeans for measuring the WBC count in an individual, and/or the level orconcentration of one or more of urinary nitrite, IL-6, glucose, proteinand plasma C-reactive protein.

The kit may additionally comprise one or more other reagents orinstruments which enable any of the embodiments of the method mentionedabove to be carried out. Such reagents or instruments include one ormore of the following: suitable buffer(s) (aqueous solutions), means toisolate HBP from sample, means to obtain a sample from the individual(such as a vessel or an instrument comprising a needle) or a supportcomprising wells on which quantitative reactions can be done. The kitmay, optionally, comprise instructions to enable the kit to be used inthe method of the invention or details regarding which individuals themethod may be carried out upon.

Therapy

The present invention also relates to the treatment of an individualidentified by a method of the invention as having a urinary tractinfection. Thus, a substance for use in the treatment of a urinary tractinfection may be used in the manufacture of a medicament for use in thetreatment of an individual identified by a method of the invention ashaving a urinary tract infection. The condition of an individualidentified by a method of the invention as having a urinary tractinfection can therefore be improved by administration of such asubstance. A therapeutically effective amount of a substance useful forthe treatment of a urinary tract infection may be given to an individualidentified by a method of the invention as in need thereof. Substancessuitable for the treatment of a urinary tract infection typicallyinclude one or more antibiotics.

The following Example illustrates the invention:

EXAMPLE Methods Study Population

This prospective study included 78 individuals (26 male and 52 female),who were admitted to the Department of Paediatric Diseases, the Hospitalof Helsingborg, Sweden, between March and June 2009. The criteria forinclusion of patients in the study were fever (temperature≧37.5° C.) orsymptoms suggesting urinary tract infection, abdominal or back pain inolder individuals and nonspecific signs such as irritability ordifficulties in feeding in younger children. Urinary tract infectionincluded both lower urinary tract infection and pyelonephritis. Patientswith neutropenia (neutrophils≦0.5×10⁹/L) or patients who had receivedantibiotics in the previous 72 hours were excluded. The project protocolwas approved by the ethics committee of Lund University Hospital andconsent was obtained from all patients by their parents. Patients weredivided into the following groups: 1) Patients with a final diagnosis ofurinary tract infection, based on bacterial culture, a urine sample witha single microorganism at ≧10⁵ colony-forming-units (CFU)/ml and typicalclinical symptoms. 2) Patients with suspected urinary tract infection,based on clinical characteristics or a urine sample with a singlemicroorganism ≧10³ CFU/ml, or a positive nitrite test. The lower cut offvalue for bacteriuria is based on recommendations from Swedish Institutefor Infectious Disease Control. 3) Patients with fever, but non-urinarytract infection 4) Patients without fever, and no urinary tractinfection.

Clinical and Laboratory Evaluations

Body temperature was recorded and CRP was analysed in plasma. Urine wascollected with midstream (75 samples) samples or suprapubic aspiration(2 samples). In one patient the technique was not registered. Analysesof urine samples were done with bacterial cultures and dipstick tests,containing tests for nitrite, white blood cells (WBC), albumin, redblood cells and glucose. Dipsticks (Multisticks® 7, Siemens) wereanalysed on a Clinitek Status (Bayer Health Care). Nitrite was presentedas either positive or negative, and WBC as semi-quantitative values in agraded scale: 0<15 leukocytes/pt urine, 1≧15 leukocytes/μL urine, 2≧70leukocytes/μL urine, 3≧125 leukocytes/μL urine, 4≧500 leukocytes/μLurine. For determination of HBP levels, urine was centrifuged within onehour of the sampling, and aliquots of the supernatants were stored at−70° C. until analysis. The concentration of HBP was determined byenzyme-linked immunosorbent assay (ELISA). Microtiter plates (NUNC) werecoated with a mouse monoclonal antibody directed against HBP in coatingbuffer (0.05M NaHCO₃, pH 9.6). Plates were washed withphosphate-buffered saline and blocked with bovine serum albumin (Sigma).Urine samples were diluted 1/40 in sample buffer (1M NaCl), added to thewells in duplicate, and incubated for 30 min at 37° C. Each plate alsocontained calibration samples of known concentration of recombinant HBP.After washing, plates were incubated with a polyclonal rabbit antiserumtowards HBP diluted 1/7000. Bound antibodies were detected by incubationwith peroxidase-conjugated antibody against rabbit IgG, Bio-Rad(1/3000). The level of HBP in each patient sample was determined bycalculating the mean optical densities of duplicates which werecorrelated to the results from the standard curve. Levels of IL-6 inurine were analysed with a sandwich-ELISA, (ELISA MAX™ Deluxe Sets),according to the manufacture's description. Urine samples were diluted1/2 in incubation buffer, and analysed in duplicates.

Statistical Analysis

Comparisons between groups were made by the non-parametricKruskal-Wallis test and Mann-Whitney-U-test for continuous variableswith skewed distributions. Correlations were made by Spearman'snon-parametric test. Areas under receiver-operator characteristic curveswere used to illustrate the power of HBP, IL-6, U-WBC and nitrite.Sensitivity, specificity, positive and negative predictive value werecalculated for HBP, IL-6 and U-WBC. The level of statisticalsignificance was defined as two-tailed p-value<0.05. The SPSS 17.0software system (SPSS) was used for statistical analyzes.

Results Characteristics of the Patients and Laboratory Signs

Seventy eight individuals were enrolled in the study. The age of thepatients ranged from 1 month to 18 years (mean 5.96 years) and 75% wereolder than 1 year. Ten patients were diagnosed with urinary tractinfection (2 with lower urinary tract infection and 8 withpyelonephritis), and all had Escherichia coli in the urine culture(group 1). Five patients had a suspected urinary tract infection basedon characteristic symptoms or laboratory results indicating urinarytract infection (group 2). Three of these 5 patients had only a moderategrowth of Escherichia colt or beta-hemolytic Streptococci group B inurine (≧10³-≦10⁵ CFU/ml), one patient had typical clinical symptoms ofcystitis but were not cultured and had a negative dipstick test, and onepatient had characteristic signs of pyelonephritis with a negative urineculture and a dipstick test that was positive for nitrite. Thirtypatients had fever but no laboratory or clinical signs of urinary tractinfection (group 3). Their urine cultures were negative or had mixedstrains of bacteria (indicative of sample contamination). Thirty-threepatients had no fever and no laboratory signs of urinary tract infection(group 4). Their urine cultures were negative. Some of these haddiagnoses (known before entering the study) like enuresis, Alportsyndrome, Henoch-Schonlein-syndrome and nephrotic syndrome.

Statistical Analysis of Results from Plasma and Urine

There were no significant differences in median age, gender,temperature, CRP in plasma, HBP in urine, IL-6 in urine, WBC or nitritein urine between group 1 (urinary tract infection) and 2 (suspectedurinary tract infection). Plasma CRP and urinary glucose did not resultin any significant differences between any groups. Urinary albumin hadsignificant differences between group 1 and 3 (fever, non-urinary tractinfection), 1 and 4 (no fever, non infection), 2 and 3, but not betweenthe others. Urinary red blood cells had significant differences betweengroup 1 and 3, 1 and 4 but not between the others. There weresignificant differences in median levels of HBP, IL-6 and WBC in urinebetween group 1 and 3. Also comparison of group 1 and 4 hadsignificantly different median levels of HBP, IL-6 and WBC in urine.There were significant differences in the urine levels of HBP, IL-6 andWBC between group 1 combined with group 2 as compared to group 3combined with group 4. (FIG. 1A-F). An interesting implication was thaturine with high concentrations of bacteria (≧10⁵CFU/ml) seemed to havehigher levels of HBP and WBC compared to urine with less or no bacteria(FIG. 2 A-B). Spearman's test with a rank correlation coefficient(rho)=0.79 indicated a relatively strong correlation between levels ofHBP and WBC in urine (FIG. 3). IL-6 did not have this strong correlationwith WBC in urine, (rho=0.38).

For calculation of sensitivity, specificity, positive predictive valueand negative predictive value group 1 and 2 was combined, referred tourinary tract infection-group and compared to the combined groups 3 and4, referred to non-urinary tract infection. Using a cut-off level of HBPof ≧32 ng/ml, the sensitivity and specificity in diagnosing urinarytract infection were 93.3% and 90.3% respectively. HBP in urine had thehighest sensitivity compared to WBC, nitrite and IL-6. HBP in urine alsohad the highest specificity compared to WBC and IL-6 (Table 2). Nitritehad the best specificity compared to the other markers. Based on the19.2% prevalence of urinary tract infection in this study the positiveand negative predictive values of HBP for prediction of urinary tractinfection were 70.0% and 98.3%, respectively (Table 2). ROC curvesdemonstrated that HBP in urine was the best predictor of urinary tractinfection with an area under curve (AUC) value of 0.94 compared to U-WBCand IL-6 (FIG. 4).

Discussion

Urinary tract infection can have serious consequences and antibioticresistance is a growing issue. Therefore, tests with higher sensitivityand specificity are needed. Several previous studies have investigatedbiomarkers in urine for the detection of urinary tract infection, likeIL-6, lactoferrin, IL-8, TNF-α, elastase and Clara cell protein. HBP inplasma has been studied as a biomarker for sepsis in adults, and datasuggested that a normal plasma level of HBP in febrile patients withsuspected infection could with high probability (negative predictivevalue 94.5%) rule out the risk of developing severe sepsis. In thepresent study, concentrations of HBP in urine was compared with urinaryIL-6, nitrite, WBC, red blood cells, albumin, glucose and plasma CRP.HBP in urine had a higher AUC value (0.94) than IL-6, nitrite and WBC,and was thus the best predictor for urinary tract infection. HBP inurine had a high negative predictive value (98.3%), and could thus ruleout disease with a high probability. The nitrite test has itslimitations with a low sensitivity. Some bacterial species can nottransform nitrate to nitrite, for example Staphylococcus saprophyticusand Enterococcus. Other reasons for false negative nitrite are shortincubation time of urine in the bladder and intake of high doses ofvitamin C. Outliers in the study exist. In group 2 (suspected urinarytract infection), one patient with symptoms of pyelonephritis andbeta-hemolytic Streptococci group-B in the urine culture (10⁴-10⁵CFU/ml) had a low level of HBP (6.3 ng/ml). This patient was alsonegative in the rapid test for urinary nitrite and WBC. Urine HBP levelswere higher in patients with urinary tract infection than in patientswith other kinds of infections, which indicates that HBP release inurine is dependent on the activation of white blood cells by forinstance bacterial infection in urine.

TABLE 1 Patient Characteristics. Clinical and laboratory data. Median,range and P-values for age, gender, CRP, HBP, temperature, U-WBC andnitrite. Group 1 Group 2 Group 3 Group 4 (n = 10) (n = 5) (n = 30) (n =33) P-value x P-value xx P-value xxx Age (years)  4.5 (0-17)  7.36(0-16)  2.0 (0-17)  8.1 (0-18) 0.322 0.225 0.299 Gender(female/male) 9/14/1 23/7 16/17 0.604 0.367 0.021 HBP (ng/ml) 72.1 (37.0-632.2) 108.3(6.4-230.9)  5.3 (3.3-121.2)  4.3 (3.2-76.5) 1.00 0.000 0.000 U-WBC¹(WBC/μL)   3 (2-4)    1 (0-3)   0 (0-3)   0 (0-2) 0.077 0.000 0.000Nitrite (pos/neg)²   1 (0-1)    0 (0-1)   0 (0-0)   0 (0-0) 0.077 0.0000.000 Temperature (° C.) 37.9 (36.7-40.0)  38.5 (37.3-41.1) 38.2(37.0-41.1) 37.0 (36.9-39.4) 0.297 0.171 0.000 CRP (ng/ml)  146 (0-201)  165 (10-184)   56 (0-190)   16 (0-169) 0.322 0.152 0.013 NOTE:P-values analyzed with the Mann-Whitney test. x = Group 1 vs 2, xx =Group 1 vs 3, xxx = Group 1 vs 4 ¹Semi-quantitative scale: 0 <15leukocytes/μL, 1 ≧15 leukocytes/μL, 2 ≧70 leukocytes/μL, 3 ≧125leukocytes/μL, 4 ≧500 leukocytes/μL ²Positive nitrite was defined as 1and negative nitrite was defined as 0.

TABLE 2 Sensitivity, Specificity, PPV and NPV of HBP, U-WBC and nitritefor prediction of UTI. (Cutoff Values of 32 ng/mL for HBP, 10 pg/mL forIL-6, 2 for U-WBC, 100 ng/ml for CRP, 0.5 for nitrite, 38° C. fortemperature). Sensitivity, % Specificity, % PPV, % NPV, % HBP 93.3 90.370.0 98.3 IL-6 73.3 84.1 52.4 93.0 U-WBC 80.0 84.8 57.1 94.3 Nitrite53.3 100 100 89.4 CRP 64.3 72.7 50 82.8 Temperature 53.3 63.3 23.7 84.4PPV, positive predictive value, NPV, negative predictive value.

1. A method of identifying whether or not an individual has a urinarytract infection, which method comprises measuring HBP in the individualand thereby determining whether or not the individual has a urinarytract infection, wherein an elevated level of HBP indicates that theindividual has a urinary tract infection, wherein an elevated level ofHBP indicates that the individual has a urinary tract infection.
 2. Amethod according to claim 1, wherein the HBP is measured in a sampletaken from the individual.
 3. A method according to claim 2, wherein thesample is a fluid sample, preferably a urine sample.
 4. A methodaccording to claim 2, wherein determining whether or not the individualhas a urinary tract infection comprises determining whether or not theconcentration of HBP is greater than 15 ng/ml, preferably greater than25 ng/ml, more preferably greater than 35 ng/ml, and most preferablygreater than 50 ng/ml in the sample.
 5. A method according to claim 2,wherein the level or concentration of HBP in the sample is increased byat least 3 fold or 4 fold relative to the baseline level orconcentration of HBP.
 6. A method according to claim 1, wherein theindividual is suspected of having a urinary tract infection.
 7. A methodaccording to claim 1, wherein the individual is a mammal.
 8. The methodof claim 7, wherein the mammal is a human.
 9. An agent for the detectionof HBP for use in determining whether or not an individual has a urinarytract infection.
 10. An agent according to claim 9, wherein the agentcomprises an HBP-specific antibody, or an HBP-binding fragment thereof.11. A method of treating an individual for a urinary tract infection,comprising; (i) determining whether or not an individual has a urinarytract infection using a method according to claim 1; and (ii)administering to an individual identified in (i) as at risk, atherapeutically effective amount of an agent suitable for the treatmentof a urinary tract infection.
 12. The method of claim 11, wherein theagent suitable for the treatment of urinary tract infection is anantibiotic.
 13. A method according to claim 1, where the HBPconcentration provides information on the severity of infection.
 14. Atest kit for use in a method for determining whether or not anindividual has a urinary tract infection, which test kit comprises anagent for the detection of HBP in an individual.